The present disclosure relates to semiconductor device manufacturing, and more particularly, to a method for forming two device wafers starting from a single base substrate.
One of the conventional methods of fabricating advanced semiconductor based devices is to epitaxially grow one or more crystalline semiconductor layers on a base substrate. The composition and doping of the epitaxially grown crystalline semiconductor layers can be controlled in order to achieve a specific electronic or opto-electronic function. Examples of the epitaxially grown crystalline semiconductor layers can be quantum well structures used for semiconductor lasers, multiple heteroepitaxial p-n junctions for use in high-efficiency photovoltaic structures, or as simple as formed p-n junctions.
Generally speaking, these highly specialized single-crystal semiconductor-containing structures are costly and time consuming to form or grow. Additionally, the single-crystal semiconductor-containing substrates themselves are relatively expensive and usually one substrate yields one device wafer. Typically, the most expensive epitaxial structures involve III-V or II-VI compound semiconductors which are generally formed using metalorgano chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) reactors. In both cases, growth usually occurs only on one side of a base substrate. Other methods of growth that are more commonly used in Group IV crystal growth such as low pressure chemical vapor deposition (LPCVD) or ultra high vacuum chemical vapor deposition (UHVCVD) batch reactors typically grow on both sides of a base substrate. The high cost of the base substrates and the growth process severely limit the throughput and cost of forming these epitaxial layers.